The Hubble Space Telescope has uncovered intriguing evidence of a hidden companion star accompanying the impressive supergiant Betelgeuse, and this finding could alter our understanding of this well-known celestial body. Betelgeuse stands out in the night sky, not only for its brilliance but also because it is just close enough for astronomers to examine it more closely than most stars, which typically appear as mere pinpoints of light. This massive red supergiant, however, exhibits unusual behavior, frequently fluctuating in brightness and dimness, making it a fascinating subject for study.
In July 2025, researchers made a groundbreaking discovery: they identified a companion star residing within the outer atmosphere of Betelgeuse. This companion, now named Siwarha, may explain the peculiar variations in Betelgeuse's luminosity. Recent observations from the Hubble Space Telescope, combined with data from ground-based observatories like the Fred Lawrence Whipple Observatory in Arizona and the Roque de Los Muchachos Observatory in the Canary Islands, have revealed a wake created by Siwarha. This exciting finding solidifies the existence of Siwarha and enhances our knowledge of stellar evolution.
According to astronomer Dupree, "With this new direct evidence, Betelgeuse gives us a front-row seat to watch how a giant star changes over time. Finding the wake from its companion means we can now understand how stars like this evolve, shed material, and ultimately explode as supernovae." By examining the joint observations, the team detected a notable "pattern of changes" in Betelgeuse, identifying the wake or trail left by Siwarha. This trail consists of material denser than the surrounding outer-atmospheric gases.
Every six years, Siwarha becomes apparent from our vantage point on Earth. When it crosses between Betelgeuse and us, its density alters the spectrum of light emitted by various elements in Betelgeuse's atmosphere, making the trail visible. Dupree likens this phenomenon to a boat gliding through water, stating, "The companion star creates a ripple effect in Betelgeuse's atmosphere that we can actually see in the data. For the first time, we're observing direct signs of this wake, confirming that Betelgeuse indeed has a concealed companion influencing its characteristics and behavior."
Looking ahead, Siwarha is expected to become observable again in 2027, and researchers are already gearing up for further observations during this event. The latest findings regarding Siwarha's wake were presented at the 247th meeting of the American Astronomical Society in Phoenix, Arizona, and are set to be published in The Astrophysical Journal.
Julian Dossett, a freelance writer based in Santa Fe, New Mexico, specializes in topics related to the rocket industry and space exploration. He also contributes travel articles to New Mexico Magazine and has received IRMA Awards for his writing in 2022 and 2024. A former staff writer for CNET, he graduated from Texas State University in San Marcos in 2011 with a bachelor's degree in philosophy and possesses an extensive collection of science fiction pulp magazines from the 1960s.
